The Trump administration's special envoy for North Korea is heading to South Korea amid growing uncertainty over the future of direct talks between Washington and Pyongyang.

The State Department says Stephen Biegun will visit Seoul this week for talks with senior South Korean officials on the status of denuclearization negotiations with the North.

But those negotiations have been stalled for months with the two sides at an impasse over next steps following the historic June summit between President Donald Trump and North Korean leader Kim Jong Un and several trips to Pyongyang by Secretary of State Mike Pompeo.

The U.S. wants the North to provide a detailed accounting of facilities that would be inspected and dismantled under a deal while the North is insisting that sanctions be lifted first.